Brief Summary

The family Hylobatidae is composed of gibbons. The family historically contained one genus, but now is split into four genera (Hylobates, Hoolock, Nomascus, and Symphalangus).[1]

Gibbons are found in tropical and subtropical rainforests from northeast India to Indonesia to southern China, including the islands of Sumatra, Borneo, and Java.[2,3] Also called the lesser apes, gibbons are unusual among primates in their locomotion, social structures, and communication systems.

Gibbons are masters of their primary mode of locomotion, brachiation, in which they use their arms to swing below branches at speeds as high as 30 km/h (18.6 mph) and with leaps of up to 10 m (32.8 ft).[4] Gibbons can walk bipedally with their long arms raised above their heads for balance.

Gibbons exhibit a generally monogamous (pair-bonded) mating system, though this pattern is known to be flexible.[5,6] Only humans and gibbons exhibit monogamy among the apes. Social groups are territorial and offspring remain with their parental group until sexual maturity.[5,6] Gibbons have one of the longest juvenile periods among primates (approximately 7 years) and exhibit a slow life history for their body size.[6]

All gibbon species produce loud and elaborate patterns of vocalizations. These "songs" are species-, sex-, and even individual-specific.[7,8] In most species, mated pairs perform "duets" in which the individual songs are layered in an established pattern.[9] It has been hypothesized that these songs function as individual identifiers, territorial advertisements, and pair-bond strengtheners.[7,10,11]